The instant invention relates to an infusion device having an injection molded drip chamber, a drop sensor, such as a light barrier or a piezoelectric member, an evaluation circuit for the output signals of the drop sensor, a power source, and a display means for optical display of an output signal provided by the evaluation circuit.
Infusion devices of the kind including a so-called drop counter are known, for example, from DE-GM No. 84 32 849, DE-GM No. 85 16 066, DE-OS No. 34 08 572, DE-OS No. 31 08 848, EP-OS No. 154 163, and DE-OS No. 34 03 969.
The object of infusion devices of the above mentioned type is to facilitate the adjustment of the dripping rate in gravity infusion. The operator (nurse) need not measure the instantaneous dripping rate in the drip chamber manually by a stop watch to adjust a control clamp. Instead, the dripping rate is measured automatically by a drop sensor, for example a light barrier or a piezoelectric member and indicated to the operator.
The rather high manufacturing costs of the known infusion devices with automatic measurement of the dripping rate and the optical display thereof is regarded as being a disadvantage. Therefore, the known measuring and display means were not offered as "disposable articles" (to be thrown away after single use), contrary to the drip chambers and hoses. Instead, they are intended for frequent and repetitive use.
Known infusion devices with electronic measurement of the dripping rate and display thereof furthermore have the disadvantage that the operator must rely on the dripping rate as indicated without having the possibility of looking into the drip chamber to see what is going on. Yet it is highly desirable that in spite of the automatic measuring and displaying the dripping rate, the operator is still able to get a full view of the drip chamber so that it can be verified by a simple glance at the instrument whether or not the resultant indicated measurement indicated makes sense.
It is an important aspect in the selling, shelfing, and stockkeeping of infusion devices which are mass-produced articles that the entire device can be handled as a compact unit. This is not possible if the drip chamber, the control clamp, and the hose on the one hand are provided as disposable articles, whereas the measuring and display means of the dripping rate are destined for multiple use (often to be used with different drip chambers, hoses, etc.).
It is, therefore, an object of the instant invention to devise an infusion device of the kind specified which can be produced as a compact unit at low cost. It is another object of the instant invention to provide an infusion device of the kind which will display the dripping rate electronically and also give the operator the opportunity of direct visual verification of the dripping condition inside the drip chamber.